Apparatus for recovering eyesight utilizing stereoscopic video and method for displaying stereoscopic video

ABSTRACT

This invention provides a stereo image displaying method and eyesight recovery apparatus which stimulates the eye muscles and is inexpensive and simple.  
     An image for the left and the right eye are displayed on the screen  50  of an electronic device  2  alternately, an observer wears spectacles  4  which open and close in synchronism with the display of these images to produce a convergence angle and parallax to obtain a 3-D image. A 3-D image display device is used to enable the observer to focus his/her right and left eyes on the images of a 3-D image. A 3-D image  10   a  is displayed at a position close to the spectacles  4  and then gradually moved away from it. The eyesight recovery apparatus comprises a movement control unit  10  for moving a 3-D image  10   b  at a distance close to the spectacles  4  and a repetition control unit  23  for repeating the receding and approach movements. When the observer wearing the spectacles  4  tries to always focus on the 3-D images  10   a  and  10   b  on the screen  50 , his/her ciliary bodies and eyeball moving muscles around his/her eyes are stimulated, thereby recovering his/her eyesight.

FIELD OF THE INVENTION

[0001] The present invention relates to a stereo image displaying methodand eyesight recovery apparatus which stimulate the eye muscles of anobserver when he/she looks at a three-dimensional (3-D) perspectiveimage displayed on a VDT electronic display device through spectacleswith shutters or without spectacles.

BACKGROUND OF THE INVENTION

[0002] Due to the spread of personal computers, the popularization of TVgames, the use of portable telephones as a necessity of life and thecontinuous appreciation of TV programs in recent years, people look atthe screen of a VDT (Visual Display Terminal) from a distance of lessthan 1 m very frequently. Therefore, the population of personal computertype short-sighted people is sharply increasing. To cure this personalcomputer type short-sightedness, an MD-SS eyesight recovery and trainingapparatus which has been developed by an ophthalmologist is used

[0003] As shown in FIG. 6, in the eyesight recovery and trainingapparatus 30, a groove 33 is formed in a long table mounted on a base 31horizontally and a target body 34 is set in such a manner that it canmove along this groove 33. The target body 34 consists of a flat plate35 and a strut 36, and a Randolt ring is drawn on the white flat plate35. The Randolt ring is a mark used for a general eye test, and a upper,lower, left or right part of the ring is cut away. The strut 36 is movedalong the groove 33 in a horizontal direction by a predetermined driveunit together with the flat plate 35, and a trainee sits opposite to theflat plate 35 with his/her chin applied to a square frame 39 beforehim/her.

[0004] The flat plate 35 can approach up to 10 cm before the eyes of thetrainee within the square frame 39 and can recede up to 2 m from theeyes. In the training method, for a short-sighted trainee, the flatplate 35 is first moved from 10 cm before the eyes of the trainee withinthe square frame 39 and moved faster in the receding direction, forexample, up to 2 m in 3 seconds.

[0005] When the flat plate 35 is to be returned from 2 m away from thetrainee within the square frame 39, the moving speed of the flat plate35 is slowed down in the approaching direction, for example, up to 10 cmbefore the eyes in 12 seconds. For a far-sighted trainee, the flat plate35 is moved at reverse speeds. This training is carried out for threeminutes each time. By chasing the flat plate 35 with the both eyes ofthe trainee, the ciliary bodies and eyeball moving muscles of thetrainee are trained to form an image of the outside world on the retinaeof the eyes.

[0006] For a direction and distance training method, a 15-point sheet 40shown in FIG. 7 is used. On the 15-point sheet 40, there are shownnumerals 1 to 5 at an upper position from left to right at equalintervals, numerals 6 to 10 at the middle from left to right at equalintervals and numerals 11 to 15 at a lower position from left to rightat equal intervals. The trainee holds the 15-point sheet with his/herboth hands and tries to see numerals 1 to 15 sequentially by movinghis/her eyeballs while turning his/her face toward the numeral 8. Then,he/she tries to see numerals 1 and 2 at the same time and up to numerals13 and 14 sequentially by moving his/her eyeballs.

[0007] Thereafter, he/she tries to see numerals 1, 2 and 3 at the sametime and up to 13, 14 and 15 sequentially by moving his/her eyeballs.Further, he/she tries to see numerals 1, 2, 3 and 4 at the same time andup to numerals 13, 14 and 15 sequentially by moving his/her eyeballs.The number of numerals to be seen at the same time is increased, or theorder of numerals to be seen is reversed. This test is repeated for 10minutes or more each day. Thus, the ciliary bodies and eyeball movingmuscles are trained.

[0008] Although the conventional MD-SS eyesight recovery and trainingapparatus is very effective in the recovery of eyesight, a trainee mustgo to a clinic. Therefore, a trainee who is busy cannot benefit from theapparatus. Although the apparatus can be purchased, it is expensive and2 m or more long, a large space in a house is required to install it.Although an apparatus employing a direction and distance training methodis simple, inexpensive, effective and handy, the number of trainees whocontinue training with the apparatus is decreasing due to laziness.

[0009] It is an object of the present invention to provide to a stereoimage displaying method and eyesight recovery apparatus which stimulatethe eye muscles and which enable a trainee who is busy and wishes torecover his/her eyesight and even a trainee who is lazy in eyesightrecovery training to continue training without fail and which are simplein structure, inexpensive and effective.

SUMMARY OF THE INVENTION

[0010] The present invention has been made to solve the above problem.

[0011] According to a first aspect of the present invention, there isprovided an to a stereo image displaying method comprising the steps of:

[0012] displaying a 3-D image at a position close to spectacles using a3-D image display device which displays an image for the left eye and animage for the right eye on an electronic display screen alternatively,allows an observer wearing spectacles which open and close insynchronism with the display of these images to see the images toproduce a convergence angle and parallax so as to obtain the 3-D imageand makes his/her right and left eyes focus on the images in order torecognize the 3-D image;

[0013] gradually moving the 3-D image away from the spectacles;

[0014] moving the 3-D image at a distance close to the spectacles in theopposite direction; and

[0015] repeating the receding/approaching movements.

[0016] According to a second aspect of the present invention, ineyesight recovery apparatus which displays an image for the left eye andan image for the right eye on an electronic display screenalternatively, allows an observer wearing spectacles which open andclose in synchronism with the display of these images to see the imagesto produce a convergence angle and parallax so as to obtain the 3-Dimage and makes his/her right and left eyes focus on the images in orderto recognize the 3-D image, there is provided an eyesight recoveryapparatus which comprises a movement control unit for displaying the 3-Dimage at a position close to the spectacles, gradually moving the 3-Dimage away from the spectacles, and moving the 3-D image at a distanceclose to the spectacles in the opposite direction; and a repetitioncontrol unit for repeating the receding/approaching movements tostimulate the ciliary bodies and eyeball moving muscles of the observerwhen he/she always tries to focus on this 3-D image.

[0017] According to a third aspect of the present invention, in eyesightrecoverry program which displays an image for the left eye and an imagefor the right eye on an electronic display screen alternatively, allowsan observer wearing spectacles which open and close in synchronism withthe display of these images to see the images to produce a convergenceangle and parallax so as to obtain the 3-D image and makes his/her rightand left eyes focus on the images in order to recognize the 3-D image,there is provided an eyesight recovery apparatus which comprises amovement control unit for displaying the 3-D image at a position closeto the spectacles, gradually moving the 3-D image away from thespectacles, and moving the 3-D image at a distance close to thespectacles in the opposite direction; and a repetition control unit forrepeating the receding/approaching movements to stimulate the ciliarybodies and eyeball moving muscles of the observer when he/she alwaystries to focus on this 3-D image.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a diagram showing the whole appearance of the eyesightrecovery apparatus of the present invention;

[0019]FIG. 2 is a circuit diagram of the eyesight recovery apparatus ofthe present invention;

[0020]FIG. 3 is a diagram for explaining a case where a 3-D perspectiveimage is used in the eyesight recovery method of the present invention;

[0021]FIG. 4 is a diagram for explaining that the eyesight recoverymethod of the present invention is a direction/distance training method;

[0022]FIG. 5 is a diagram showing the type of a 3-D image of theeyesight recovery apparatus of the present invention;

[0023]FIG. 6 is a diagram for explaining that the conventional eyesightrecovery method is a perspective method using an actual object; and

[0024]FIG. 7 is a diagram for explaining the conventionaldirection/distance training method using an actual object.

DETAILED DESCRIPTION

[0025] An image of an object is formed on human right and left eyes witha parallax that even the same object is shifted in a horizontaldirection. The parallax of an object close to the eyes is larger thanthe parallax of an object far away from the eyes. As the object isfarther away from the eyes, the parallax becomes smaller. Further,although the right and left eyes form a convergence angle for an objectto be seen, the convergence angle of an object close to the eyes islarger than the convergence angle of an object far away from the eyes.The convergence angle becomes smaller as the object is farther away fromthe eyes. The human brain forms a three-dimensional (3-D) image of anobject from its convergence angle and parallax and judges the distanceof the object.

[0026] Meanwhile, a 3-D namely stereo image display device produces aconvergence angle and parallax in a displayed image electronically. Whena specific 3-D image is to be seen, the ciliary bodies and eyeballmoving muscles of the right and left eyes become active to focus on theimage (virtual image). According to the experiments of the inventor ofthe present invention, a trainee felt tired around his/her eyes as muchas he/she received training with the MD-SS eyesight recovery andtraining apparatus and direction/distance training method.

[0027] As for the eyesight recovery method and apparatus of the presentinvention, a case where the eyesight recovery apparatus used is adesk-top personal computer will be described hereinbelow. FIG. 1 showsthe whole appearance of the eyesight recovery apparatus. In FIG. 1, thiseyesight recovery apparatus comprises a 3-D image display device, logiccircuit 1, display unit 2, infrared light emitting unit 3, spectacleswith shutters 4 and keyboard 5. Since the spectacles with shutters 4which are used to see a 3-D image and the infrared light emitting unit 3are already described in detail in U.S. Pat. No. 5,808,588, so theirdescriptions are omitted.

[0028] The logic circuit 1 is a main body and comprises a reading unitsuch as CD-ROM (disk-type high-density reading and recording medium), FD(floppy disk) or DVD and a hard disk as a memory. The CD-ROM, FD or HDstores an eyesight recovery program (software) together with otherprograms. The eyesight recovery program shows an image similar to theflat plate 35 used in the conventional MD-SS eyesight recovery andtraining apparatus or a 3-D image similar to the numerals shown in the15-point sheet used in the direction/distance training method.

[0029] The circuit configuration of the eyesight recovery apparatus willbe detailed with reference to FIG. 2. In FIG. 2, the eyesight recoveryapparatus comprises a display unit 2, speaker 9, spectacles 4, keyboard5, infrared light emitting unit 3 and logic circuit 1. The logic circuit1 comprises a CPU 23, basic memory 6, image memory 7, sound memory 8,first electronic switch 10, second electronic switch 11, first modegenerating unit 12, second mode generating unit 13 and infrared lightemitting unit 3.

[0030] The base memory 6 stores software which is input from CD-ROM orFD. This software is separated according to an instruction from the CPU23 to send 3-D image data to the 3-D image memory 7 and sound data tothe sound memory 8. The image memory 7 consists of a left memory 14 anda right memory 15, and the first electronic switch 10 switches betweenthe left memory 14 and the right memory 15 according to a timing signalP from the CPU 23 to read image data. This timing signal P is also sentto the infrared light emitting unit 3.

[0031] The second electronic switch 11 switches between the first modegenerating unit 12 and the second mode generating unit 13 according to aswitch signal Q from the CPU 23. The first mode generating unit 12 has anormal display speed of 60 cycles and the second mode generating unit 13has a high display speed of 120 cycles.

[0032] The CPU 23 switches the display unit 2 from a normal scan mode toa double scan mode (high speed). As the structure of a 3-D image TV isdisclosed in detail by JP-A 8-20551, JP-A 9-200804 and U.S. Pat. No.5,510,832, so its description is omitted. A personal computer has ascreen of a non-interlace type high-resolution ordinary scan modewhereas an expensive digital display has a large-sized screen of anon-interlace type high resolution and high-speed scan mode in automaticresponse to the characteristics of an input video signal, and the modeis switched by the electronic switch 11 based on an instruction from theCPU 23.

[0033] Thus, an image for the left eye and an image for the right eyeare displayed alternately on the screen 50 of the 3-D image displaydevice. The spectacles 4 with shutters are provided with liquid crystalshutters corresponding to the right and left liquid crystal lenses, andthe shutters are opened or closed in accordance with an infraredopening/closing signal from the infrared light emitting unit 3. In thebrain, images from the right and left eyes are compounded to recognize a3-D image on the display unit 50. Since the left and right eyes see 30Hz images, respectively, a smooth 3-D image can be recognized naturally.

[0034] The spectacles 4 are not always required but the spectacles 4 inuse help for the right and left eyes to recognize the right and lefteyes image respectively on the display unit 50.

[0035] A description is subsequently given of the operation of theapparatus. When an operator of office equipment or game player sits infront of a personal computer and starts to use the personal computer,the eyesight recovery program is read from the CD-ROM, FDD, HD or thebase memory 6 by the CPU 23. The player becomes an observer or traineeautomatically. When the menu includes a 3-D perspective image and 3-Ddirectional image and a 3-D perspective image is selected, an imageshown in FIG. 3 is displayed (conceptually) or when a 3-D directionalimage is selected, an image shown in FIG. 4 is displayed on the displayunit 2 (conceptually).

[0036] In the case of a 3-D perspective image, in FIG. 3, a 3-D image 10a is displayed at a position close to the spectacles 4 on the displayunit 2 (the image is displayed on the display unit 2) and then displayedas if it gradually went away from the spectacles 4. After the passage ofa predetermined time, a 3-D image 10 b is displayed. The trainee wearingthe spectacles 4 adjusts his/her focusing point so that he/she can seethe 3-D image 10 b clearly.

[0037] When the 3-D image 10 a is a character, the trainee tries to readthe character, whereby his/her ciliary bodies and eyeball moving musclesbecome active automatically to adjust the thickness of his/hercrystalline lenses so that an image of the character is focused onhis/her retinas accurately. To read the character, the ciliary bodiesand eyeball moving muscles become active to focus the 3-D image on theretina. In the case of a 3-D perspective image, the trainee can inputthe receding speed v1, the moving distance L and the specification ofsound during training. For example, the trainee can input a movingdistance L of 10 m, a receding speed v1 of 10 m/6 seconds and anapproaching speed v2 of 10 m/12 seconds from the keyboard 5.

[0038] As for other forms of the 3-D image 10 a, as shown in FIG. 5, ananimal like a fish, cat, heart, star, circle, triangle, square or other3-D character can be selected. The size of the 3-D image 10 a can be setfreely and its color can also be selected from red, blue, yellow,purple, orange, pink or color striped pattern. Sound data from the soundmemory 8 is sent to the speaker 9 after predetermined processing soundduring training can be selected from the recitation of a poem composedby Tohson Shimazaki, classical music, Japanese popular song, Westernpopular song, jazz, folk song, wind sound, wave sound and the like.

[0039] By setting the number of seconds for dividing the moving distanceL of the 3-D image to a large or small value, the receding speed of the3-D image is adjusted. Since a young short-sighted trainee has thedifficulty of seeing an object at a distance, the receding speed v1 isset high (the number of seconds is set to a small value) in FIG. 3 inorder to improve the momenta of the ciliary body and the eyeball movingmuscle. Since a young short-sighted trainee can see an object close athand, the approaching speed v2 is set low (the number of seconds is setto a large value) in order to moderate the momenta of the ciliary bodyand the eyeball moving muscle.

[0040] Since an aged far-sighted trainee can see an object at a distancewell, the receding speed v 1 is set low (the number of seconds is set toa large value) in order to moderate the momenta of the ciliary body andthe eyeball moving muscle. Since an aged far-sighted trainee has thedifficulty of seeing an object close at hand, the approaching speed v2is set high (the number of seconds is set to a small value) in order toimprove the momenta of the ciliary body and the eyeball moving muscle.Before starting office work with a personal computer or during a recessor after the end of the recess, this training is carried out for about 3or 4 minutes. In a method similar to this direction/distance trainingmethod, as shown in FIG. 4, the 3-D image 10 a approaches very close toan upper left position of the left eye and then recedes toward the deepcenter of the screen.

[0041] The receding speed and approaching speed of the 3-D image can beset to appropriate values from the keyboard 5. The trainee tries tochase this 3-D image 10 a with his/her both eyes. The trainee tries tosee (focus on) a character, for example, as the 3-D image 10 a by movinghis/her both eyeballs while he/she turns his/her face forward. Bychasing the 3-D image with his/her both eyes, the ciliary bodies andeyeball moving muscles of his/her both eyes move actively or try to moveactively (expand or shrink).

[0042] Thereafter, the 3-D image 10 b approaches toward the upper rightdirection of the right eye gradually from the deep center of the screen.Although the actual 3-D image is displayed on the screen, as the botheyes of the trainee must focus on its virtual image to see the 3-Dimage, the ciliary bodies and eyeball moving muscles of the both eyesmust move as when the actual object recedes or approaches. Further, the3-D image approaches very close to the upper right direction of theright eye and gradually recedes toward the deep center of the screen.

[0043] Then, the 3-D image 10 b approaches toward the lower rightdirection of the right eye from the deep center of the screen.Similarly, the 3-D image approaches very close to the lower leftdirection of the left eye and gradually recedes toward the deep centerof the screen. The approaching and receding positions, speeds and movingorders can be suitably set from the keyboard 5 according to the eyesightof the trainee.

[0044] Even with this method, the size of the 3-D image 10 a can befreely set from the keyboard 5, and the color of the 3-D image can beselected from red, blue, yellow, purple, orange, pink and color stripedpattern. The sound during training can be selected from, for example,the recitation of a poem composed by Tohson Shimazaki, classic music,Japanese popular song, Western popular song, jazz, folk song, wind soundand wave sound.

[0045] Before the start of office work with a personal computer orduring or at the end of a recess, the CPU 23 always reads this eyesightrecovery software from the base memory 6 and executes this software.This training must be carried out for about 3 or 4 minutes by settingthe minimum time with a timer or the like each time he/she sits in frontof a personal computer.

[0046] The electronic display device 2 may be a desk-top electroniccomputer (CRT type personal computer), notebook type electronic computer(liquid crystal type small-sized personal computer), portable telephone(PHS or other telephone with a liquid crystal display), portableelectronic terminal (PDA), helmet type electronic display device (HMD),electronic display device with built-in spectacles, or TV game device(TV receiver used as a display device) if it has a 3-D image displayfunction. Further, the 3-D image display device may be a reticular type,parallax barrier type or double-image splitter type 3-D image displaydevice which does not need spectacles. The trainee tries to read the 3-Dimage 10 a, whereby his/her ciliary bodies and eyeball moving musclesbecome active automatically, various muscles around eyeball arestimulated.

[0047] The device for stimulating the ciliary bodies and eyeball movingmuscles gives eyesight recovery performance.

[0048] Since the eyesight recovery apparatus can be used by anyone atany time and anywhere, for example, at an office, home or commuter trainas described above, a person who is very busy and wishes to recoverhis/her eyesight and a person who is lazy in training for the recoveryof his/her eyesight can continue training without fail. Since theapparatus of the present invention simply incorporates a program orsoftware and has a 3-D image display function, his/her personal computercan be used as the apparatus. Therefore, the apparatus is inexpensiveand can be expected to achieve a great effect. Looking at an electronicdisplay device is now part of routine work and therefore it isapprehended that the population of short-sighted people and people witheyestrain and astigmatism is growing. In contrast to this, when theseelectronic devices are provided with a 3-D image display function andthe eyesight recovery method and apparatus of the present invention areapplied to these devices, the recovery of eyesight can be carried outduring working hours automatically and forcedly.

1. a stereo image displaying method comprising the steps of: displayinga 3-D image at a position close to spectacles using a 3-D image displaydevice which displays an image for the left eye and an image for theright eye on an electronic display screen alternatively, allows anobserver wearing spectacles which open and close in synchronism with thedisplay of these images to see the images to produce a convergence angleand parallax so as to obtain the 3-D image and makes his/her right andleft eyes focus on the images in order to recognize the 3-D image;gradually moving the 3-D image away from the spectacles; moving the 3-Dimage at a distance close to the spectacles in the opposite direction;and repeating the receding/approaching.
 2. The stereo image displayingmethod according to claim 1, wherein sound is reproduced during thereceding and approaching movements.
 3. The stereo image displayingmethod according to claim 1, wherein the approaching speed of the 3-Dimage differs from the receding speed of the 3-D image.
 4. The stereoimage displaying method according to claim 1, wherein the receding andapproaching movements of the 3-D image are carried out between the frontof the spectacles and the center portion of the screen.
 5. The stereoimage displaying method according to claim 1, wherein the receding andapproaching movements of the 3-D image are carried out between the upperleft or upper right portion of the spectacles and the center portion ofthe screen.
 6. The stereo image displaying method according to claim 1,wherein the receding and approaching movements of the 3-D image arecarried out between the lower left or lower right portion of thespectacles and the center portion of the screen.
 7. The stereo imagedisplaying method according to claim 1, wherein the receding andapproaching speeds of the 3-D image differ from each other and are setaccording to the eyesight of the observer.
 8. The stereo imagedisplaying method according to claim 1, wherein the number ofrepetitions of the receding and approaching movements of the 3-D imageis set according to the eyesight of the observer.
 9. The stereo imagedisplaying method according to claim 1, wherein the 3-D image issupplied to the 3-D image display device as a program from a memorywhich stores the 3-D image.
 10. The stereo image displaying methodaccording to claim 1, wherein the 3-D image is a character, symbol orpattern.
 11. The stereo image displaying method according to claim 1,wherein a character, symbol or pattern is shown itself 3-dimensionallyas the 3-D image.
 12. The a stereo image displaying method according toclaim 1, wherein the 3-D image is turned itself during its receding andapproaching movements.
 13. In a 3-D image display device which displaysan image for the left eye and an image for the right eye on anelectronic display screen, allows an observer to see the images by eacheye respectively to produce a convergence angle and parallax so as toobtain the 3-D image and makes his/her right and left eyes focus on theimages in order to recognize the 3-D image, an eyesight recoveryapparatus which comprises a movement control unit for displaying the 3-Dimage at a position close to the eyes, gradually moving the 3-D imageaway from the eyes, and moving the 3-D image at a distance close to theeyes in the opposite direction; and a repetition control unit forrepeating the receding/approaching movements to stimulate the ciliarybodies and eyeball moving muscles of the observer in order to recoverhis/her eyesight when he/she always tries to focus on this 3-D image.14. In a 3-D image display device which displays an image for the lefteye and an image for the right eye on an electronic display screenalternatively, allows an observer wearing spectacles which open andclose in synchronism with the display of these images to see the imagesto produce a convergence angle and parallax so as to obtain the 3-Dimage and makes his/her right and left eyes focus on the images in orderto recognize the 3-D image, an eyesight recovery apparatus whichcomprises a movement control unit for displaying the 3-D image at aposition close to the spectacles, gradually moving the 3-D image awayfrom the spectacles, and moving the 3-D image at a distance close to thespectacles in the opposite direction; and a repetition control unit forrepeating the receding/approaching movements to stimulate the ciliarybodies and eyeball moving muscles of the observer in order to recoverhis/her eyesight when he/she always tries to focus on this 3-D image.15. The eyesight recovery apparatus according to claim 13, wherein the3-D image display device comprises a sound reproduction unit forreproducing sound during the receding and approach movement.
 16. Theeyesight recovery apparatus according to claim 13, wherein the 3-D imagedisplay device comprises a speed control unit for controlling movingspeed during the receding and approach movement.
 17. The eyesightrecovery apparatus according to claim 13, wherein the 3-D image displaydevice comprises a repetition control unit for controlling the number ofrepetitions of the receding and approaching movements of the 3-D image.18. The eyesight recovery apparatus according to claim 13, wherein theelectronic display device is a desk-top personal computer, notebook typepersonal computer, portable telephone, portable electronic terminal,helmet type electronic display device, electronic display device withbuilt-in spectacles or a TV game device.
 19. In a 3-D image displaydevice which displays an image for the left eye and an image for theright eye on an electronic display screen alternatively, allows anobserver wearing spectacles which open and close in synchronism with thedisplay of these images to see the images to produce a convergence angleand parallax so as to obtain the 3-D image and makes his/her right andleft eyes focus on the images in order to recognize the 3-D image, aneyesight recovery program which comprises a movement control unit fordisplaying the 3-D image at a position close to the spectacles,gradually moving the 3-D image away from the spectacles, and moving the3-D image at a distance close to the spectacles in the oppositedirection; and a repetition control unit for repeating thereceding/approaching movements to stimulate the ciliary bodies andeyeball moving muscles of the observer in order to recover his/hereyesight when he/she always tries to focus on this 3-D image.